1. Field of the Invention
The present invention relates to a rotary electric machine which is loaded on vehicles, such as passenger cars and trucks.
2. Related Art
A type of rectifier that has been known is disclosed in Japanese Patent Application Laid-Open Publication No. 2002-519987, for example. This type of rectifier has a two-layer structure in which a positive fin (positive heat sink) and a negative fin (negative heat sink) are disposed along the direction of the rotary shaft. In this type of rectifier, the base portion of each of negative diodes is press-fitted to the negative fin so as to be projected out of the end face of the negative fin into the direction of the frame, for direct contact with the base of the frame. With this structure, the heat generated by the negative diodes can be transferred to the frame to enhance the cooling properties.
Also, a type of vehicle alternator that has been known is disclosed in Japanese Patent Application Laid-Open Publication No. 06-078504, for example. This type of vehicle alternator has a structure in which a heat-reflective member is disposed at an inner peripheral surface of the frame (rear bracket), which surface faces the stator coil, via a heat insulator. With this structure, heat can radiate effectively from the diodes of the rectifier to the frame (rear bracket).
The structure disclosed in Japanese Patent Application Laid-Open Publication No. 2002-519987 is based on the premise that the temperature of the rectifier is higher than that of the frame. Accordingly, if the temperature of the rectifier becomes lower than that of the frame due to reduction of electrical resistance of the rectifying elements, for example, heat will contrarily be transferred from the frame to the rectifier.
As a result, the temperature of the rectifier will be undesirably raised due to the heat transferred from the frame. A countermeasure that can be taken for reducing the temperature of the frame in this case may be to combine the structure disclose in Japanese Patent Application Laid-Open Publication No. 06-078504 with the structure disclosed in Japanese Patent Application Laid-Open Publication No. 2002-519987.
However, preventing the heat transfer from the stator coil to the frame may hinder cooling of the stator coil, because the cooling is actually produced by permitting the heat to escape from the stator coil to the frame. Thus, when the above structures are combined, concerns may arise that the cooling properties of the entire vehicle alternator may be deteriorated. Therefore, the countermeasure mentioned above may not be preferable.